Police say 57-year-old Alan Powell died Tuesday night after being attacked by 42-year-old Guy Hunnewell in an exercise area of the Maine State Prison.

WARREN, Maine (AP) _ Maine's medical examiner says an inmate serving a life sentence for murder died of blunt force trauma to the head in an attack at the Maine State Prison.

Police say 57-year-old Alan Powell died Tuesday night after being attacked by 42-year-old Guy Hunnewell in an exercise area of the prison, located in Warren. The medical examiner on Thursday ruled the death a homicide.

Powell was serving a life sentence for sexually assaulting, stabbing and strangling a 65-year-old woman in her Waterville apartment in 1989.

Hunnewell is serving a 40-year sentence for fatally stabbing his former girlfriend in a jealous rage in 1997.